A new approach for the synthesis of electrocatalytically active CoFe2O4 catalyst for oxygen reduction reaction

Synthesis of non-precious electrocatalyst for the reduction of oxygen is of significant interest in the development of electrochemical energy conversion devices. Herein, we demonstrate a new, low-cost, and facile non-hydro thermal approach for the synthesis of electrocatalytically active spinel CoFe2O4 by thermal annealing of the multirnetal complex, potassium cobalt hexacyanoferrate [K2CoFe(CN)(6)]. The as-synthesized CoFe2O4 is characterized by spectroscopic, electron microscopic and electrochemical techniques. The polyhedral-shaped crystalline CoFe2O4 particles have size ranging from 200 to 300 nm. The CoFe2O4 catalyst is integrated with reduced graphene oxide (rGO) and its electrocatalytic activity toward oxygen reduction reaction is evaluated. The integrated hybrid catalyst rGO/CoFe2O4 favors the 4-electron reduction of oxygen to water at low overpotential in alkaline pH with Tafel slope of 63 mV dec(-1). The hybrid catalyst (rGO/CoFe2O4) has high durability and methanol tolerance. The catalytic performance is superior to that of the as-synthesized CoFe2O4 and rGO. The enhanced electrocatalytic performance is ascribed to the synergistic effect of CoFe2O4 and rGO, large surface area and high electronic conductivity. The ideal integration of CoFe2O4 with electronically conducting rGO favor the facile diffusion and promote the electron transfer for the reduction of oxygen.